Ice making machine

ABSTRACT

Ice making machine for producing pieces of ice being provided with a hollow evaporator supplied with a refrigerant and a plurality of partitions secured onto the outer surface of the evaporator so as to be vertically extended from the top to the bottom thereof, thereby forming water channels therebetween. During the period of ice formation, water is supplied to the channels and refrigerant is supplied to the evaporator so that portions of the water freeze to form pieces of ice. During the period of harvesting, the water supply is discontinued and heated refrigerant vapor is provided in the evaporator to remove the pieces of ice therefrom.

United States Patent Hosoda et al.

[ 51 Apr. 25,1972

1 1 ICE MAKING MACHINE [73] Assignee: Hitachi, Ltd., Tokyo, Japan [22] Filed: June 12, 1970 [21] Appl. No.: 45,662

[30} Foreign Application Priority Data June 13, 1969 Japan ..44/55084 [52] U.S. C1 ..62/l37, 62/180, 62/348, 137/392 [51] Int. Cl. ..F25c l/l4 [58] Field of Search ..62/348, 347, 71, 515, 137, 62/180 [56] References Cited UNITED STATES PATENTS 2,637,177 5/1953 Reedall ..62/347 UX 3,206,944 9/1965 Gallo ..62/347 2,891,387 6/1959 Cocanour ..62/348 X 2,598,429 5/1952 Pownall 62/348 X 2,997,861 3/1961 Kocher et al. ..62/347 Primary Examiner-William E. Wayner Attorney-Craig, Antonelli & Hill 57 ABSTRACT lce making machine for producing pieces of ice being provided with a hollow evaporator supplied with a refrigerant and a plurality of partitions secured onto the outer surface of the evaporator so as to be vertically extended from the top to the bottom thereof, thereby forming water channels therebetween. During the period of ice formation, water is supplied to the channels and refrigerant is supplied to the evaporator so that portions of the water freeze to form pieces of ice. During the period of harvesting, the water supply is discontinued and heated refrigerant vapor is provided in the evaporator to remove the pieces of ice therefrom.

15 Claims, 11 Drawing Figures PATENTEDAPR 25 I972 SHEET 10F 3 FIG. I

// //l ll/ FICELE INVENTORb TAISEI Hosonll, moss unuHASm BY HIRDICHI OSIYHIH AND KKIUO IONA ATTORNEYS ICE MAKING MACHINE BACKGROUND OF THE INVENTION The present invention relates to an ice making machine, and more particularly, to a commercial-type ice making machine for use in hotels, restaurants and the like.

One type of conventional ice making machine for making a number of pieces of ice consists of an ice forming plate disposed in inclined relationship with respect to the bottom of a compartment, a water distribution system for passing a uniform stream of water on the outer surface of the ice forming plate from the upper portion downwardly thereof, an evaporator located in contact with the opposed surface of the ice forming plate opposite to the outer surface thereof and an ice cutting means including heating mesh wires placed at a position adjacent to the ice forming plate.

Such a conventional type of machine carries out basically two steps of operation. First, a water stream is provided on the outer surface of the ice forming plate, and at the same time, liquid refrigerant is provided into the evaporator, so that a portion of the water stream flowing over the outer surface of the plate may be frozen to form a slab of ice thereon. As time passes, the slab of ice grows larger. Secondly, the supply of water on the ice forming plate is discontinued after a certain amount of ice has been built up and the evaporator is then provided with heated refrigerant vapor. Due to this second step, the surface of the ice forming plate is gradually warmed, so that the slab of ice formed on and contacted to the surface of the plate is melted, thereby falling onto the surface of the heating mesh wires. Thus, the slab of ice is cut into a plurality of cubes and falls into an ice storage vessel.

The conventional machines are thus necessarily provided with ice cutting means including heating mesh wires, thereby making it difficult to provide a simplified and compact ice making machine. Furthermore, there are disadvantages in that the efficiency of ice making is very low since a certain amount of ice is converted back to water during the cutting operation, while a large amount of power is consumed by the heating mesh wires for cutting the slab ofice into cubes.

SUMMARY OF THE INVENTION It is an aim of the present invention to overcome the abovementioned problems and disadvantages of the conventional ice making machines.

The underlying problems are solved in accordance with the present invention by providing an ice making machine comprising a hollow pillar-shaped evaporator into which refrigerant is supplied, a plurality of partitions vertically disposed on the outer surface of the evaporator so as to be extended from the top to the bottom thereof, a water distribution system for providing a uniform water stream over the outer surface of the evaporator, and refrigerant supply means, which, in the period of refrigeration cycle, operationally supplies low pressure liquid refrigerant to the evaporator so as to cool the evaporator, thereby producing pieces of ice separated by the plural partitions on the outer periphery of the evaporator. During the harvesting cycle, the refrigerant supply means operationally supplied heated refrigerant vapor to the evaporator so that the pieces of ice may be removed from the evaporator and directly fall into an ice storage vessel.

Accordingly, it is an object of the present invention to provide an improved ice making machine which directly forms pieces of ice without any means for cutting a slab of ice.

Another object of the present invention is to provide an ice making machine with a high ice-making efficiency and low power consumption.

It is still a further object of the present invention to provide an ice making machine of relatively compact and simplified construction.

BRIEF DESCRIPTION OF THE DRAWING These and further features, advantages and objects of the ing description when taken in conjunction with the accompanying drawing which shows, for purposes of illustration only, several embodiments in accordance with the present invention and wherein:

FIG. 1 is a front view, partly in elevation and partly in section, of the ice making machine in accordance with the present invention;

FIG. 2(a) is an enlarged fragmentary perspective view of an ice forming member which is an essential part of the ice making machine of the present invention;

FIGS. 2(b) and 2(a) are a front sectional view of FIG. 2(a) and a side view of a partition mounted on the ice forming member, respectively;

FIG. 3 is a schematic view of a refrigerant supply circuit in accordance with the present invention;

FIG. 4 is a schematic view of the electrical control circuit in accordance with the present invention;

FIGS. 5(a)(d) are cross sections of the other shaped evaporators in accordance with the present invention; and

FIG. 6 is a perspective view of another partition in accordance with the present invention.

DETAILED DESCRIPTION OF THE DRAWING Referring now to the drawing and, in particular, to FIG. 1, there is shown an ice making machine having a first compartment 1 and a second compartment 2. A compressor 3, a condenser (not shown) and part of the controls are placed in the second compartment 2. An ice forming member 4, an ice storage vessel 5, and a water distribution system which includes a water tank 6, a water supply 7, a water distribution pipe 8 and a sump 9 are located in the first compartment. The tank 6 is provided with water from a source of water supply (not shown) through a line 10. The level of water in the tank 6 is detected by suitable detector means 13 to control the refrigeration and harvesting cycles which will be described in greater detail herein below. The water level detector means 13 comprises, for example, three needles 131, 132 and 133 which are vertically inserted from the top walls of the tank 6 into the water therein as shown in FIG. 4, and the length of each of the needles is different from each other. Valve 11 is disposed in the line 10 between the tank 6 and the source of water supply in order to regulate the quantity of water flowing therethrough.

Pump 12 is placed in the tank 6 to supply water from the tank 6 by means of the pipe 7 to the water distribution pipe 8 having a plurality of openings formed at the under side of the pipe so as to provide a plurality of water streams over the surface of the ice forming member 4 described herein below. Water from the ice forming member 4 falls to the sump 9 placed below the member 4. Mesh wire screen 91 is provided over the sump 9 to permit passage of water therethrough while preventing passage of the pieces of ice. The sump 9 has a water outlet for leading water into the tank 6. Thus, water is continuously circulated in the closed circuit including the tank 6, the pipe 7, the distribution pipe 8, the ice forming member 4 and the sump 9.

On a partition 14 between the first and second compartments 1 and 2, there is located an ice storage vessel 5 into which pieces of ice removed from the ice forming member 4 fall during the harvesting cycles. The amount of the pieces of ice is detected by a weight switch 15 generally mounted at the wall of the first compartment 1. A switching device 51 which is sensitive to temperature in the ice storage vessel is disposed at a suitable place, for example, at the position of the inner surface of the vessel 5. The switching device 51 is connected with control circuits (described herein after) to effectively prevent melting of the pieces of ice stored in the vessel 5.

Referring now to FIGS. 2(a) and 2(b), there is shown an ice forming member 4 in accordance with the present invention. A hollow pillar-shaped evaporator 41 which is made of a material having high thermal conductivity such as, for example, steel and constituting the ice forming member 4 has top and bottom walls, opposed side walls 413, 414 and end walls 411, 415. One end wall 411 is provided with an inlet 412 through which refrigerant enters into the evaporator 41, and the other end wall 415 is provided with an outlet 416 through which refrigerant is lead out therefrom. Both side walls 413, 414 are preferably inclined slightly with respect to a vertical line so that the distance a between the lower ends thereof is shorter than the distance between the upper ends so that water is allowed to flow in contact therewith.

On the surfaces of both side walls, a plurality of partitions 42 composed ofa material such as, for example, resin having a lower thermal conductivity than that of the evaporator are mounted by any suitable bond or mechanical connection so as to be vertically extended from the top to the bottom of the side walls, and the partitions are placed apart and parallel with respect to each other so as to form water stream passages therebetween. The evaporator 41 in accordance with the present invention is attached with side boards 451 and 452 made of a material such as, for example, a resin having lower thermal conductivity than that of side walls 413, 414 of the evaporator so as to form parts of the ice forming plates 42 of the evaporator. The side boards 451 are projected upwardly from the top roof X of the evaporator 41 and are vertically opposed to each other or vertically inclined to each other as shown in FIGS. 2(1)), and 5(a)-(d). Similarly, the side boards 452 are projected downwardly from the bottom floor Y of the evaporator as shown in FIGS. 2(1)), 5(a) and 5(d). A single side board 452 is also operable as shown in FIGS. 5(b) and 5(0).

The pieces of ice may be, therefore, firstly formed on the side walls 413 and 414 of the evaporator 41 and gradually grown toward and over the resin boards 451 and 452. The side boards 451 and 452 have low thermal conductivity so that they are cooled less in comparison with the side walls 413, 414 of the evaporator 41. Accordingly, a portion of the grown pieces of ice on the side boards 45] and 452 do not firmly cling therewith, so that the pieces of ice may be easily removed from the ice forming plate during the harvesting cycles. Each partition 42 is preferably so designed that the thickness thereof is reduced horizontally from its contact point with the side walls outwardly as well as vertically from its top to the bottom as shown in FIG. 2(c). Such a partition shape effects easy removal of grown pieces of ice from the surfaces ofthe side walls during the harvesting.

Roof 43 is provided over the top wall 417 of the evaporator 41 in order that the water falling from the distribution pipe 8 may be lead onto the side walls 413, 414 thereof and may uniformly flow in contact with the surfaces of the side walls. The distribution pipe 8, which is located above the roof 43, is provided with a plurality of openings through which a water stream may be continuously supplied to the evaporator during the ice forming cycles. It is desirable to attach mutually opposed side boards 44 on the top portions of the partitions 42 and with a small distance C from the contact portion as shown in FIG. 2(b) in order to prevent scattering of the water. Located below the ice forming member 4 is a sump 9 which is provided with a mesh wire screen 91 on the surface thereof. Water flowing over the outer surfaces of the side walls of the evaporator 41 falls onto the sump 9 through the screen 91 and returns to the water tank 6.

During the ice forming cycles, the evaporator 41 is supplied with liquid refrigerant through the inlet 412 so as to be cooled at the surfaces of the opposed side walls 413, 414 thereof at substantially a freezing temperature. At the same time, water is continuously supplied by the pump 12 from the tank 6, through pipe 7, distribution pipe 8 to the ice forming member 4. Therefore, portions of the water stream flowing between the respective partitions 42 on the outer surfaces of the side walls 413, 414 of the evaporator 41 are gradually frozen'to finally form separate pieces of ice. Thus, cooled water not frozen into ice is continuously recirculated over the ice forming plates. This then reduces the time required for ice formation. When ice pieces are sufficiently grown, the period of harvesting cycles is commenced, wherein the evaporator 41 is provided with heated refrigerant vapor through the inlet 412, so that the surfaces of the ice forming plates are heated and the pieces of ice are removed therefrom as shown by a dotted shape in FIG. 2(b). Controls for the refrigeration and harvesting cycles are described in greater detail herein below.

Referring now to FIG. 3, there is schematically shown the refrigerant supply circuit which includes a compressor 3, an evaporator 41 and a condenser 20. Refrigerant compressed by the compressor 3 is supplied to the condenser 20 and than cooled by air or water. Refrigerant is thus converted from the gaseous state to the liquid state and is supplied, by way of capillary tube 21, to the evaporator 41 which is placed in the first compartment 1. Liquid refrigerant evaporates and absorbs heat from the surrounding atmosphere therearound in the compartment 1 and is converted into the gaseous state. Then, the refrigerant returns to the compressor 3. A valve 23 is placed at a downstream position of the refrigerant in a line 25 from the compressor 3. A heated refrigerant vapor line 26 branches from the valve 23 and terminates upstream of the evaporator 41 in the line 24 between the evaporator 41 and the capillary tube 21 so that hot refrigerant bypasses from the compressor 3 to the evaporator 41. The solenoid valve 23 switches the refrigerant to bypass either the line 26 or the lines 24 and 25 as well as the condenser 20 and the capillary tube 21. In the harvesting cycles, the valve 23 is so operated as to provide refrigerant from the compressor 3 to the evaporator 41 through the line 26, and in the ice forming cycles, to provide refrigerant through the condenser 20 and the capillary tube 21.

FIG. 4 shows an electrical circuit for controlling the abovementioned water distribution system, the refrigerant supply circuit and the other equipment associated with the ice making machine of the present invention. The compressor motor unit 31 is supplied with operating power from an A.C. power source 50 through a temperature control, that is the switching device 51 which is disposed at the suitable place in the ice storage vessel 5 to detect temperatures therein. If temperatures in the ice storage vessel 5 exceed the freezing point of water, the controller 51 becomes operative and switches to the on position, while it switches to the off position at temperatures below the freezing point of water. An alternating current from the power source 50 is also supplied to the primary winding of a transformer 52 by means of weight switch 15 located on the inner wall of the first compartment 1. The weight switch 15 is maintained in its closed state until a suffcient amount of ice has been stored in the ice storage vessel 5 so as to exceed a certain predetermined weight. When the weight of the ice stored is over a predetermined value, for example, several kilograms, the weight switch 15 opens the circuit and thus the ice making function is stopped.

An induced voltage appears across the secondary winding of the transformer 52 and it is applied to a pair of opposed diagonal nodes F and G of a full wave rectifying diode bridge circuit 53 through the water level detector 54 in the tank 6 so that a rectified output representative of the A.C. voltage applied is obtained between the other nodes. The water level detector 54 has three needles 131, 132 and 133 vertically disposed from the inside wall of the tank into the water therein. The detection heights of the respective needles are different from each other. A first detecting needle 131, the longest of the three, is connected with one terminal of a secondary winding of the transformer 52. A third detecting needle 133, the shortest of the three is connected with one node G of the diode bridge circuit 53. Between the second detecting needle 132 having medium length and the third detecting needle 133, a relay contact 551 is inserted which conducts on-off operations in response to current flowing through a relay coil 552. Between the diagonal nodes H and l of the bridge are connected the parallel circuit of a smoothing capacitor 56 and the relay coil 552.

A change-over switch 57 is also operated in accordance with current flowing through the relay coil 552. In the nonenergized period of the relay coil 552, the switch 57 is closed to a contact A, so that A.C. current provided from the A.C. power supply 50 can flow through an exciting coil 231 connected in series therewith. Under such conditions, the valve 23 located at the connecting point of the refrigerant lines 25 and 26 is operated to pass heated refrigerant vapor from the compressor 3 to the evaporator 41 through the line 26. When the relay coil 552 is energized with DC. current from the bridge circuit 53, the change-over switch 57 is closed to contact B so that A.C. current from the power supply 50 can flow through a motor unit 121 for pump 12 shown in FIG. 1. An exciting coil 111 for controlling the water supply valve 11 and a switch of a temperature controller 58 placed on the evaporator 41 are serially connected with the motor unit 121. When the exciting coil 111 is supplied with A.C. current, the valve 11 is opened to supply the water flow source to the tank 6. The temperature controller 58 acts to perform on-off operations according to whether the temperature at the surface of the evaporator 41 is or is not over 20 C.

The operation of the above-mentioned ice making machine in accordance with the present invention will now be considered. In an initial condition, the temperature controller 51 is in its on-position while the temperature in the first compartment 1 as well as ice storage vessel 5 is above the freezing point of water. The weight switch is closed since no piece of ice is stored in the vessel 5. The switch 551 is opened and the change-over switch is closed to the contact A for the reason that the relay coil 552 is not excited until the water level in the tank reaches the extreme point of the shortest nee dle 133.

Under such an initial condition, the change-over valve 23 connects the compressor 3 to the line 24. Therefore, compressed refrigerant vapor from the compressor 3 is directly supplied to the evaporator through the line 26. The temperature at the surface of the evaporator 41 gradually rises, and when the temperature exceeds the predetermined value, for example C., the temperature controller 51' disposed on the evaporator 11 turns into the on-position. Accordingly, current supplied from the power supply 50 flows through the exciting coil 111, so that the valve 11 is opened to permit passage of the water from the water supply to the tank 6. Although the exciting current also flows through the motor unit 121, the power supplied thereto is too small to drive the motor unit, because the power from the source 50 is mostly applied to the exciting coil 111 having a larger impedance compared to that of the armature winding of the motor unit 121.

When the water level in the tank 6 is increased to reach the extreme point of the third needle 133, the passage between the terminals C and E is electrically conducted through water in the tank so that the induced voltage across the secondary winding of the transformer 52 may be applied between the nodes F and G of the diode bridge circuit 53. The rectified voltage appearing between the nodes H and I is smoothed by the capacitor 56 and then applied across the relay coil 552. Accordingly, the switch 551 is closed to maintain the application of the induced voltage to the bridge circuit until the water level is over the second needle point and the change-over switch is closed on the contact B.

When the change-over operation of the switch 57 is conducted from the contact A to B, valve 23 operates to close the refrigerant line 26, thereby preventing passage of heated refrigerant vapor therethrough and opening the refrigerant line between the compressor 3 and the condenser 20. The heated high pressure refrigerant vapor from the compressor 3 is, therefore, condensed and liquified by the condenser 20 and then its pressure is reduced by the capillary tube 21 and is thereafter provided to the evaporator 41. At the same time, the motor unit 121 commences its rotation by the application thereto of operational current from the power source 50 through the change-over switch 57, so that the pump 12 begins to supply water from the tank 6 onto the surfaces of the ice forming plate of the evaporator 41. On the other hand, since the series connected circuit of the exciting coil 111 and the temperature controller 58 is short-circuited by the changeover switch 57, the exciting coil 111 cannot be activated. Thus, water supply from the supply source to the tank 6 may be discontinued.

Water carried from the tank 6 in the distribution pipe 8 is discharged through the openings thereof onto the roof 43 of the evaporator 41 and then flows in contact with the outer surfaces of the ice forming plates on which the partitions 42 are vertically disposed so as to form channels for the water streams. Portions of water flowing over the surfaces of the ice forming plates of the evaporator 41 are frozen to form pieces of ice since the evaporator 41 is cooled substantially below the freezing point of water by the refrigerant supplied thereinto. Cooled water not formed into ice falls in the sump 9 and returns to the tank 6 and is recirculated over the ice forming plates to increase the amount of ice formed thereon.

When the water level in the tank 6 becomes lower than the position of the extreme point of the second needle 132, the electrical passage between the terminals C and D is disconnected so as to discontinue the supply of A.C. current from the transformer 52 to the diode bridge circuit 53. Thus, the relay coil 552 terminates its on-position and the switch 551 returns to its on-position and the change-over switch 57 is closed on the contact A to provide A.C. current from the power source 50 to the exciting coil 231 for the valve 23. Under such conditions, the motor unit 121 for the pump 12 is released from its energized state, so that the supply of water from the tank to the ice forming plates is discontinued.

At the same time, the change-over valve 23 acts to connect the compressor 3 to the evaporator 41 through the line 26, while disconnecting the passage between the compressor 3 and the condenser 20. Accordingly, the evaporator 41 is now supplied with heated refrigerant vapor to remove pieces of ice from the outer surfaces of the ice forming plates. The pieces of ice fall into the ice storage vessel 5 as shown by the dotted line in FIG. 2(b). Once all the pieces of ice have been removed from the ice forming plates, the temperature of the surfaces thereof is gradually raised. If its temperature becomes higher than 20 C., the temperature controller switchs into the onposition to energize the exciting coil 111 for the valve 11 for again supplying water from the supply source to the tank 6.

By repeating the above-mentioned operations of the ice forming and harvesting cycles, the amount of the pieces of ice stored in the ice storage vessel 5 is gradually increased. When the weight of the stored pieces of ice exceeds a predetermined value, the weight switch 15 disposed on the outer surface of the first compartment 1 operates to open the control circuit in order that the ice forming function may be discontinued thereafter. To prevent the pieces of ice stored in the ice storage vessel 5 from melting, the temperature controller 51 switches to its on-position to drive the compressor motor 31 whenever the temperature in the ice storage vessel exceeds the freezing point of water. Although here the changeover switch is closed on the contact A, the solenoid valve 23 may not be energized since the weight switch 15 is opened so as not to provide A.C. power thereto. The refrigerant on the compressor 3 is, therefore, transferred through the condenser 20 to the evaporator 41. Thus, the surface of the evaporator 41 is not provided with water and the evaporator 41 refrigerates the surrounding atmosphere. Therefore, temperatures in the first compartment 1 may be maintained lower than the freezing point of water so as to prevent the melting of the pieces of ice stored in the vessel 5.

The above-described ice making machine is so constructed that the side walls of the evaporator 41 are used as the ice forming plates and water from the tank 6 is directly supplied thereon, whereby the efficiency of ice forming is very much higher than that of conventional devices. Furthermore, the present invention directly produces pieces of ice without producing first a slab of ice, and therefore, it does not require any cutting devices. Consequently, the machine of the present invention is of low cost, low power consumption, and of compact configuration.

While we have shown and described one embodiment in accordance with the present invention, it is to be clearly understood that the same is susceptible of numerous changes and modifications as will be apparent to one skilled in the art. For example, while the evaporator 41 as described above is of hollow pillar-shape, differently shaped evaporators shown crosssectionally in FIGS. (a)(d) may be used for the ice making machine in accordance with the spirit of the present invention. Among these modifications, however, it is necessary that the uppermost distance be between the side walls 413 and 414 of the evaporator 41 is longer than the lowermost distance A thereof. Furthermore, the partition 42 disposed on the ice forming plate can be also modified to various shapes, one of which is illustrated in FIG. 6. This partition is designed so that the uppermost extension E is longer than the lowermost extension D. The above relations between the distances A and B and between the extensions D and E are effective for the easy removal of the grown pieces of ice on the ice forming plate during the harvesting cycles. Therefore, we do not wish to be limited to the details shown and described herein but intend to cover all such changes and modifications encompassed by the scope of the present invention.

We claim:

1. Ice making machine for producing pieces of ice compris-' hollow evaporator means made of a material having a relatively high thermal conductivity, the evaporator means adapted to be supplied with refrigerant and having substantially vertically disposed side walls;

side boards secured onto top and bottom surfaces of the evaporator so as to be extended from said surfaces upwardly and downwardly, respectively, and the side boards and the side walls of the evaporator means forming ice making plates on which pieces of ice are to be formed;

a plurality of partitions secured onto the ice making plates so as to be vertically extended from the top to the bottom of the plates and spaced apart from each other in substan tially parallel manner to form water stream channels therebetween, the side boards and partitions being made of material having relatively lower thermal conductivity than that of the evaporator means; said partitions having a thickness which is reduced horizontally from the contact point thereof with the side walls of the evaporator means outwardly as well as vertically from the top to the bottom thereof;

water distribution means for supplying water onto the evaporator means so as to flow through the channels on the ice making plates in contact therewith and for circulating the supply of water; and

refrigerant supply circuit means for selectively supplying heated refrigerant vapor and liquid refrigerant to the evaporator means.

2. Ice making machine according to claim 1, wherein the uppermost distance between the side walls of the evaporator means is relatively longer than the lowermost distance thereof.

3. Ice making machine according to claim 1, wherein a single side board extends downwardly from the bottom surface of the evaporator means.

4. Ice making machine according to claim 1, wherein the uppermost extension of each partition is relatively longer than the lowermost extension thereof.

5. An ice making machine according to claim 1, further including an electrical control circuit for controlling the operation of said water distribution means and said refrigerant supply circuit means comprising means, responsive to the supply of water within said water distribution means and the temperature within said machine, for effecting and cutting off the supply of water and refrigerant to said evaporator means.

6. An ice making machine according to claim 5, wherein said machine further includes a water storage means for storing water to be supplied to said evaporator means and includes water level sensor means disposed within said water storage means;

said electrical control circuit including a source of power, a temperature responsive switch connected thereto and respective electrically controlled first and second valves, coupled with said water distribution means and said refrigerant supply circuit means, and being coupled to said power source through said temperature responsive switch and to said water storage means through said water level sensor means for controlling the flow of water and refrigerant to said evaporator means, in response to the temperature within said machine and the level of water within said water storage means.

7. An ice making machine according to claim 6, wherein said electrical control circuit further comprises a power coupling means, coupled to said source of power, for supplying current to be conducted through the water level sensor means of said water storage means, a first switching means responsive to the current flowing through said water level sensor means for effecting exclusive application of energizing power to said first and second electrically controlled valves.

8. An ice making machine according to claim 7, further including a pump and a motor therefor, for pumping water from said water level storage means, through said water distribution means, said first switch means comprises a first switch connector connected in series with said second electrically controlled valve for energizing said second electrically controlled valve in response to a first predetermined level of water in said water storage means.

9. An ice making machine according to claim 8, further comprising a second switch means, coupled to said first electrically controlled valve for controlling the energization of said first electrically controlled valve in response to the temperature of said evaporator means.

10. An ice making machine according to claim 9, wherein said first switch means further includes an additional switch connected in series with said pump motor for energizing said motor while preventing the operation of said second electrically controlled valve.

11. An ice making machine according to claim 10, wherein said water level sensor means comprises a plurality of conductors each displaced with respect to each other in the direction of the surface of the water within said water storage means, a first of which being connected to said power coupling means, while at least one other conductor is connected to one terminal ofa bridge circuit, another terminal of which, opposite to said one terminal, being connected to said power coupling means.

12. An ice making machine according to claim 11, wherein said first switching means comprises a first relay coil connected to a first pair of opposite terminals of said bridge circuit, a second pair of which being connected to said one and another of opposite terminals thereof, and wherein said bridge comprises a rectifier bridge, said first switch means includes a pair of conductors respectively connected to said first electrically controlled valve and to said motor, while the movable connector thereof is coupled through said power source to one of said contacts in response to the energization of said relay coil.

13. An ice making machine according to claim 12, wherein said first switch means further includes a second pair of switch contacts and a movable arm therefor for controlling the water level at which said relay coil becomes energized.

14. An ice making machine according to claim 13, wherein said ice making machine further includes means for receiving ice from said evaporator means and further including a wait switch responsive to the wait of said received ice for deenergizing said electrical control means in response to a predetermined quantity of ice therein, and further including a compressor motor coupled to said power supply for driving said refrigerant supply means for maintaining the temperature within said machine at a predetermined level.

15. An ice making machine according to claim 14, further including a control temperature responsive switch connecting said power source to the input of said electrical control circuit 

1. Ice making machine for producing pieces of ice comprising: hollow evaporator means made of a material having a relatively high thermal conductivity, the evaporator means adapted to be supplied with refrigerant and having substantially vertically disposed side walls; side boards secured onto top and bottom surfaces of the evaporator so as to be extended from said surfaces upwardly and downwardly, respectively, and the side boards and the side walls of the evaporator means forming ice making plates on which pieces of ice are to be formed; a plurality of partitions secured onto the ice making plates so as to be vertically extended from the top to the bottom of the plates and spaced apart from each other in substantially parallel manner to form water stream channels therebetween, the side boards and partitions being made of material having relatively lower thermal conductivity than that of the evaporator means; said partitions having a thickness which is reduced horizontally from the contact point thereof with the side walls of the evaporator means outwardly as well as vertically from the top to the bottom thereof; water distribution means for supplying water onto the evaporator means so as to flow through the channels on the ice making plates in contact therewith and for circulating the supply of water; and refrigerant supply circuit means for selectively supplying heated refrigerant vapor and liquid refrigerant to the evaporator means.
 2. Ice making machine according to claim 1, wherein the uppermost distance between the side walls of the evaporator means is relatively longer than the lowermost distance thereof.
 3. Ice making machine according to claim 1, wherein a single side board extends downwardly from the bottom surface of the evaporator means.
 4. Ice making machine according to claim 1, wherein the uppermost extension of each partition is relatively longer than the lowermost extension thereof.
 5. An ice making machine according to claim 1, further including an electrical control circuit for controlling the operation of said water distribution means and said refrigerant supply circuit means comprising means, responsive to the supply of water within said water distribution means and the temperature within said machine, for effecting and cutting off the supply of water and refrigerant to said evaporator means.
 6. An ice making machine according to claim 5, wherein said machine further includes a water storage means for storing water to be supplied to said evaporator means and includes water level sensor means disposed within said water storage means; said electrical control circuit including a source of power, a temperature responsive switch connected thereto and respective electrically controlled first and second valves, coupled with said water distribution means and said refrigerant supply circuit means, and being coupled to said power source through said temperature responsive switch and to said water storage means through said water level sensor means for controlling the flow of water and refrigerant to said evaporator means, in response to the temperature within said machine and the level of water within said water storage means.
 7. An ice making machine according to claim 6, wherein said electrical control circuit further comprises a power coupling means, coupled to said source of power, for supplying current to be conducted through the water level sensor means of said water storage means, a first switching means responsive to the current flowing through said water level sensor means for effecting exclusive application of energizing power to said first and second electrically controlled valves.
 8. An ice making machine according to claim 7, further including a pump and a motor therefor, for pumping water from said water level storage means, through said wateR distribution means, said first switch means comprises a first switch connector connected in series with said second electrically controlled valve for energizing said second electrically controlled valve in response to a first predetermined level of water in said water storage means.
 9. An ice making machine according to claim 8, further comprising a second switch means, coupled to said first electrically controlled valve for controlling the energization of said first electrically controlled valve in response to the temperature of said evaporator means.
 10. An ice making machine according to claim 9, wherein said first switch means further includes an additional switch connected in series with said pump motor for energizing said motor while preventing the operation of said second electrically controlled valve.
 11. An ice making machine according to claim 10, wherein said water level sensor means comprises a plurality of conductors each displaced with respect to each other in the direction of the surface of the water within said water storage means, a first of which being connected to said power coupling means, while at least one other conductor is connected to one terminal of a bridge circuit, another terminal of which, opposite to said one terminal, being connected to said power coupling means.
 12. An ice making machine according to claim 11, wherein said first switching means comprises a first relay coil connected to a first pair of opposite terminals of said bridge circuit, a second pair of which being connected to said one and another of opposite terminals thereof, and wherein said bridge comprises a rectifier bridge, said first switch means includes a pair of conductors respectively connected to said first electrically controlled valve and to said motor, while the movable connector thereof is coupled through said power source to one of said contacts in response to the energization of said relay coil.
 13. An ice making machine according to claim 12, wherein said first switch means further includes a second pair of switch contacts and a movable arm therefor for controlling the water level at which said relay coil becomes energized.
 14. An ice making machine according to claim 13, wherein said ice making machine further includes means for receiving ice from said evaporator means and further including a wait switch responsive to the wait of said received ice for deenergizing said electrical control means in response to a predetermined quantity of ice therein, and further including a compressor motor coupled to said power supply for driving said refrigerant supply means for maintaining the temperature within said machine at a predetermined level.
 15. An ice making machine according to claim 14, further including a control temperature responsive switch connecting said power source to the input of said electrical control circuit and wherein said power coupling means comprises a transformer, the primary winding of which is coupled to said power source and the secondary winding of which is connected to one of said conductors and to said bridge circuit. 